word problem - distance and speed T took 5 h to drive 470km from point x to point y.For part of the trip, he drove at 100 km/h, and for the other part, he drove at 90 km/h. How far did he drive at each speed. So I know that speed 1 distance + speed 2 distance = 470 km. I don't know the rest, however. thanks

Hint: There are two unknowns; $T_1$, the time for which he drove on the first part (at $100$ km/h); $T_2$, the time for which he drove on the second part (at $90$ km/h). What is the sum $T_1+T_2$? What is the sum $100T_1+90T_2$? The answers give you 2 equations for the two unknowns.